swarm: remove unnecessary reqno for pending request tracking (libp2p#2460)

* swarm: remove unnecessary reqno for pending request tracking

* use struct{} instead of bool for addrs map

* use struct{} for pendingRequests map

Author: sukunrt

p2p/net/swarm/dial_worker.go

@@ -56,9 +56,6 @@ type addrDial struct {
 	conn *Conn
 	// err is the err on dialing the address
 	err error
-	// requests is the list of pendRequests interested in this dial
-	// the value in the slice is the request number assigned to this request by the dialWorker
-	requests []int
 	// dialed indicates whether we have triggered the dial to the address
 	dialed bool
 	// createdAt is the time this struct was created
@@ -74,13 +71,9 @@ type dialWorker struct {
 	peer peer.ID
 	// reqch is used to send dial requests to the worker. close reqch to end the worker loop
 	reqch <-chan dialRequest
-	// reqno is the request number used to track different dialRequests for a peer.
-	// Each incoming request is assigned a reqno. This reqno is used in pendingRequests and in
-	// addrDial objects in trackedDials to track this request
-	reqno int
-	// pendingRequests maps reqno to the pendRequest object for a dialRequest
-	pendingRequests map[int]*pendRequest
-	// trackedDials tracks dials to the peers addresses. An entry here is used to ensure that
+	// pendingRequests is the set of pendingRequests
+	pendingRequests map[*pendRequest]struct{}
+	// trackedDials tracks dials to the peer's addresses. An entry here is used to ensure that
 	// we dial an address at most once
 	trackedDials map[string]*addrDial
 	// resch is used to receive response for dials to the peers addresses.
@@ -101,7 +94,7 @@ func newDialWorker(s *Swarm, p peer.ID, reqch <-chan dialRequest, cl Clock) *dia
 		s:               s,
 		peer:            p,
 		reqch:           reqch,
-		pendingRequests: make(map[int]*pendRequest),
+		pendingRequests: make(map[*pendRequest]struct{}),
 		trackedDials:    make(map[string]*addrDial),
 		resch:           make(chan dialResult),
 		cl:              cl,
@@ -232,10 +225,8 @@ loop:
 				continue loop
 			}
 
-			// The request has some pending or new dials. We assign this request a request number.
-			// This value of w.reqno is used to track this request in all the structures
-			w.reqno++
-			w.pendingRequests[w.reqno] = pr
+			// The request has some pending or new dials
+			w.pendingRequests[pr] = struct{}{}
 
 			for _, ad := range tojoin {
 				if !ad.dialed {
@@ -253,7 +244,6 @@ loop:
 					}
 				}
 				// add the request to the addrDial
-				ad.requests = append(ad.requests, w.reqno)
 			}
 
 			if len(todial) > 0 {
@@ -263,7 +253,6 @@ loop:
 					w.trackedDials[string(a.Bytes())] = &addrDial{
 						addr:      a,
 						ctx:       req.ctx,
-						requests:  []int{w.reqno},
 						createdAt: now,
 					}
 					dq.Add(network.AddrDelay{Addr: a, Delay: addrDelay[string(a.Bytes())]})
@@ -328,20 +317,14 @@ loop:
 					continue loop
 				}
 
-				// request succeeded, respond to all pending requests
-				for _, reqno := range ad.requests {
-					pr, ok := w.pendingRequests[reqno]
-					if !ok {
-						// some other dial for this request succeeded before this one
-						continue
+				for pr := range w.pendingRequests {
+					if _, ok := pr.addrs[string(ad.addr.Bytes())]; ok {
+						pr.req.resch <- dialResponse{conn: conn}
+						delete(w.pendingRequests, pr)
 					}
-					pr.req.resch <- dialResponse{conn: conn}
-					delete(w.pendingRequests, reqno)
 				}
 
 				ad.conn = conn
-				ad.requests = nil
-
 				if !w.connected {
 					w.connected = true
 					if w.s.metricsTracer != nil {
@@ -375,33 +358,26 @@ loop:
 // dispatches an error to a specific addr dial
 func (w *dialWorker) dispatchError(ad *addrDial, err error) {
 	ad.err = err
-	for _, reqno := range ad.requests {
-		pr, ok := w.pendingRequests[reqno]
-		if !ok {
-			// some other dial for this request succeeded before this one
-			continue
-		}
-
+	for pr := range w.pendingRequests {
 		// accumulate the error
-		pr.err.recordErr(ad.addr, err)
-
-		delete(pr.addrs, string(ad.addr.Bytes()))
-		if len(pr.addrs) == 0 {
-			// all addrs have erred, dispatch dial error
-			// but first do a last one check in case an acceptable connection has landed from
-			// a simultaneous dial that started later and added new acceptable addrs
-			c, _ := w.s.bestAcceptableConnToPeer(pr.req.ctx, w.peer)
-			if c != nil {
-				pr.req.resch <- dialResponse{conn: c}
-			} else {
-				pr.req.resch <- dialResponse{err: pr.err}
+		if _, ok := pr.addrs[string(ad.addr.Bytes())]; ok {
+			pr.err.recordErr(ad.addr, err)
+			delete(pr.addrs, string(ad.addr.Bytes()))
+			if len(pr.addrs) == 0 {
+				// all addrs have erred, dispatch dial error
+				// but first do a last one check in case an acceptable connection has landed from
+				// a simultaneous dial that started later and added new acceptable addrs
+				c, _ := w.s.bestAcceptableConnToPeer(pr.req.ctx, w.peer)
+				if c != nil {
+					pr.req.resch <- dialResponse{conn: c}
+				} else {
+					pr.req.resch <- dialResponse{err: pr.err}
+				}
+				delete(w.pendingRequests, pr)
 			}
-			delete(w.pendingRequests, reqno)
 		}
 	}
 
-	ad.requests = nil
-
 	// if it was a backoff, clear the address dial so that it doesn't inhibit new dial requests.
 	// this is necessary to support active listen scenarios, where a new dial comes in while
 	// another dial is in progress, and needs to do a direct connection without inhibitions from